Ruthenium boride reinforced extra-ultra coarse grain WC-Co hard alloy and preparation method thereof

Abstract

The invention relates to the technical field of hard alloys, and particularly discloses a ruthenium boride reinforced ultra-ultra coarse grain WC-Co hard alloy and a preparation method thereof in order to solve the problems of low strength and hardness and poor toughness of an ultra-ultra coarse grain alloy product caused by difficult control of grain size in an existing ultra-ultra coarse grain alloy preparation process. The ultra-coarse grain WC-Co hard alloy comprises the following raw materials: 0.5-5% of ruthenium-boron mixed powder, 5-10% of cobalt powder and the balance of tungsten carbide particles. Wherein the number ratio of ruthenium atoms to boron atoms in the ruthenium-boron mixed powder is 1: (0.5-1.5), and the carbon adjusting range of the total mass of tungsten and carbon in the tungsten carbide particles is 6.08-6.20 wt%. The problems that WC particles are excessively crushed and Co phases are non-uniformly distributed are solved by utilizing high-energy stirring dry mixing without adding a grinding body and combining a flexible wet grinding process with extremely short time and extremely low ball-to-material ratio, and Ru powder and B powder are introduced and combined with a special sintering process, so that the effects of high toughness, high hardness, high heat conductivity and the like of the ultra-coarse grain alloy are achieved.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, and more specifically, to a ruthenium boride-strengthened ultra-coarse-grained WC-Co cemented carbide and its preparation method. Background Technology

[0002] Ultra-coarse-grained cemented carbide refers to WC-Co cemented carbide with an average grain size (dwc) between 5 and 7.9 μm. When dwc ≥ 8 μm, it is defined as extra-ultra-coarse-grained cemented carbide. Due to its unique microstructure, ultra-coarse-grained cemented carbide exhibits excellent impact resistance, wear resistance, and thermal fatigue resistance, and has great development potential in rock drilling, stamping dies, and hot rolling mills. Compared with other coarse-grained alloys with comparable cobalt content, extra-ultra-coarse-grained cemented carbide with dwc ≥ 8 μm has higher toughness, red hardness, thermal conductivity, and thermal fatigue resistance, and will show better service performance in rock drilling and mining applications. However, extra-ultra-coarse-grained alloys with coarser grains, thicker cobalt layers, and better toughness often exhibit lower strength and hardness due to the lack of fine-grain strengthening, which greatly limits the application areas and service life of extra-ultra-coarse-grained cemented carbide.

[0003] Furthermore, the traditional wet milling process for preparing ultra-coarse alloys has serious technical drawbacks, namely, it is difficult to ensure that the coarse grain size of WC is coarse while the cobalt phase is uniformly distributed. Existing technologies for preparing coarse-grained cemented carbides can be mainly divided into two categories: flexible ball milling combined with nanopowder dissolution, and chemical coating methods that eliminate the wet milling step. For example, patent CN110387497A discloses a method for preparing ultra-coarse-grained WC-Co cemented carbides by combining flexible ball milling and nanopowder dissolution. The flexible ball milling method achieves the purpose of preparing coarse grains by shortening the milling time and reducing the ball-to-material ratio. However, excessively short milling times and excessively low ball-to-material ratios can lead to uneven distribution of the Co phase, and in severe cases, cause porosity in the alloy microstructure. On the other hand, moderately increasing the ball-to-material ratio and extending the milling time makes it difficult to guarantee the average grain size of WC. For example, patent CN118291829A discloses a method for preparing ultra-coarse alloys by reducing cobalt salts. Although the chemical coating method can eliminate the wet grinding process and better preserve the grain size of WC, due to its complex composition, the cobalt salt is prone to insufficient reduction. In addition, a large amount of toxic and harmful gases are generated during the reduction reaction, causing a huge burden on waste gas treatment or environmental pollution problems.

[0004] In summary, existing technologies for preparing ultra-coarse-grained alloys with a dwc ≥ 8 μm suffer from problems such as difficulty in ensuring grain size, complex and difficult-to-control preparation processes, and relatively low strength and hardness. Therefore, there is an urgent need for a simple, environmentally friendly preparation process that can produce ultra-coarse-grained WC-Co cemented carbides with both high hardness and toughness, in order to expand the application areas and service life of ultra-coarse-grained cemented carbides. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that the existing ultra-coarse grain alloy preparation process is difficult to control the grain size, which leads to low strength, hardness and poor toughness of ultra-coarse grain alloy products.

[0006] This invention is achieved through the following technical solution: This invention provides a ruthenium boride-strengthened ultra-coarse-grained WC-Co cemented carbide, wherein the raw materials, by mass percentage, include 0.5-5% ruthenium-boron mixed powder, 5-10% cobalt powder, and the balance being tungsten carbide particles; The ruthenium-boron mixed powder has an atomic ratio of 1:0.5-1.5, and the total mass of tungsten and carbon in the tungsten carbide particles ranges from 6.08 to 6.20 wt%.

[0007] Preferably, the FSSS of the tungsten carbide particles is 25~30μm.

[0008] The present invention also provides a method for preparing the above-mentioned ruthenium boride-strengthened ultra-coarse-grained WC-Co cemented carbide, comprising the following steps: S1 Take the raw materials according to the specified amount, place them in a mixer, and stir at a speed of 1000~5000 rpm to carry out the first activation treatment and obtain the premix; S2 The premixed material, molding agent, wet grinding media, and grinding media are placed in a ball mill and wet-milled to undergo a second activation treatment to obtain a mixed slurry; the mixed slurry is dried, sieved, and pressed to obtain a pressed compact; S3 The compact is placed in a sintering furnace, subjected to gradient heating, dewaxing and sintering, then cooled with the furnace and removed to obtain the ultra-coarse-grained WC-Co cemented carbide.

[0009] Preferably, in step S1, the ratio of the total volume of the raw materials to the volume of the agitator is 0.2 to 0.3.

[0010] Preferably, in step S1, the stirring time is 4~12 hours.

[0011] Preferably, in step S2, the volume ratio of the mixed slurry to the ball mill capacity is 0.4 to 0.5.

[0012] Preferably, in step S2, during wet grinding, the grinding speed is 60~80 rpm, the ball-to-material ratio is 0.5~1.2:1, and the wet grinding time is 4~10 h.

[0013] Preferably, in step S2, the grinding media is a coarse rod of Φ10.5*17mm and / or a fine rod of Φ5.5*14.4mm.

[0014] Preferably, in step S2, the pressing pressure is 10~12MPa and the holding time is 5~10s.

[0015] Preferably, in step S3, during the gradient heating, the temperature is controlled as follows: The first step is to start from room temperature, heat to 400±20℃ at a heating rate of 1~5℃ / min, and hold at that temperature for 0.3~0.7h to dewax. The second step is to heat the sample to 1100±20℃ at a heating rate of 1~5℃ / min and hold it at that temperature for 0.5~1.5h. The third step is to heat the sample to 1200±20℃ at a heating rate of 10~20℃ / min and hold it at that temperature for 0.5~1.5h. The fourth step is to heat the sample to 1400±20℃ at a heating rate of 10~20℃ / min and hold it at that temperature for 0.5~1.5h. The fifth step involves heating the material to 1460±20℃ at a heating rate of 1~5℃ / min, and introducing argon gas until the ambient pressure reaches 3~6MPa. The material is then held under these conditions for 1~4 hours to complete the dewaxing and sintering process.

[0016] The technical solution of the present invention has the following beneficial effects: The present invention proposes an ultra-coarse-grained WC-Co cemented carbide and its preparation method. By adding specific amounts of Ru powder and B powder to the WC-Co cemented carbide and combining it with a special sintering process, the RuB phase is generated in situ during the sintering process to strengthen the alloy, thus preparing an ultra-coarse-grained WC-Co cemented carbide with high toughness, high thermal conductivity and high hardness.

[0017] Furthermore, in terms of the preparation process, two activation treatments are performed sequentially. The first activation of the mixed powder is achieved by high-energy stirring dry mixing without grinding media, followed by a second activation of the material by flexible wet grinding with an extremely short time and an extremely low ball-to-powder ratio. This allows the alloy to continue alloying and densification processes smoothly during subsequent sintering, overcoming the problems of excessive crushing of WC particles and uneven distribution of the Co phase. This enables the preparation of ultra-coarse-grained alloys with good toughness, high hardness, and high thermal conductivity, expanding the application fields of ultra-coarse-grained alloy tools, extending their service life, and reducing process complexity. Attached Figure Description

[0018] Figure 1 The image shows the powder morphology of the mixed alloy powder after high-energy stirring in Example 1 under SEM. Figure 2 Metallographic image of the ultra-coarse-grained WC-6Co cemented carbide containing 0.5 wt% ruthenium boride in Example 1; Figure 3 Metallographic image of the ultra-coarse-grained WC-6Co cemented carbide containing 1.5 wt% ruthenium boride in Example 2; Figure 4 Metallographic image of WC-6Co cemented carbide containing 0.5wt% Cr3C2 in Comparative Example 2; Figure 5 The image shows the metallographic diagram of the WC-Co cemented carbide in Comparative Example 3.

[0019] Specific implementation details To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer; where the manufacturers of the instruments, equipment, reagents, or raw materials used are not specified, they are all conventional products that can be purchased commercially.

[0020] This invention provides a ruthenium boride-strengthened ultra-coarse-grained WC-Co cemented carbide, wherein the raw materials, by mass percentage, include 0.5-5% ruthenium-boron mixed powder, 5-10% cobalt powder, and the balance being tungsten carbide particles; Furthermore, in the ruthenium-boron mixed powder, the atomic ratio of ruthenium to boron is 1:0.5-1.5, the purity of ruthenium powder and boron powder is ≥99.99%, and the FSSS of both is about 1μm; the FSSS of cobalt powder is 1μm; the FSSS of tungsten carbide particles is 25~30μm, and the carbon content of the total mass of tungsten and carbon is adjusted in the range of 6.08~6.20wt%.

[0021] The preparation method of the ultra-coarse-grained WC-Co cemented carbide in this invention includes the following steps: (1) Weigh each component raw material according to the amount, put each component raw material into a high-energy stirrer protected by inert gas, without adding grinding media, and rely only on the stirring blades built into the stirrer to stir at high speed, so that the raw materials come into contact and collide with each other in the stirrer. After violent collision, the raw material powder can be mechanically interlocked to obtain a uniformly mixed premix. This process is the first activation stage of the material. The high-energy agitator has a stirring blade speed of 1000~5000rpm, a stirring time of 4~12h, and a raw material volume to agitator volume ratio of 0.2~0.3.

[0022] Since there are only stirring blades and no grinding media during the stirring process, they only serve to mix the materials and do not crush them. The resulting mixed powder of tungsten carbide, cobalt, ruthenium, and boron has the advantages of uniform material mixing and distribution, and intact tungsten carbide particles.

[0023] (2) The premixed material, molding agent, wet grinding media and grinding media are added to the ball mill together and wet grinding is carried out with a low ball-to-material ratio and short time to obtain a mixed slurry. This process is the second activation stage of the material. After wet grinding, the material is discharged, the mixed slurry is dried and sieved to obtain mixed powder, and then pressed into a blank. The molding agent is polyethylene glycol (PEG) or paraffin wax, and the amount of molding agent added is 2-3% of the total mass of the premix; the wet grinding media is alcohol, acetone or n-hexane, and 0.3-0.4L of wet grinding media corresponds to 1kg of mixture; the grinding media is Φ10.5*17mm coarse rod, Φ5.5*14.4mm fine rod, or a combination of coarse and fine rods; the wet grinding speed is 60-80rpm, the ball-to-material ratio is 0.5-1.2:1, the wet grinding time is 4-10h, and the ratio of total material to the volume of the ball mill container is 0.4-0.5 (total material refers to the sum of premix, molding agent, wet grinding media, and grinding media); The drying process employs vacuum drying or spray drying at a temperature of 70-80℃, with a sieve particle size of 40-60 mesh, a pressing pressure of 10-12 MPa, and a holding time of 5-10 seconds.

[0024] (3) The pressed blank is placed in a low-pressure sintering furnace for dewaxing and sintering, and the temperature is controlled as follows during the sintering process: The first step is to heat the sample from room temperature to 400±20℃ at a heating rate of 1~5℃ / min and hold it at that temperature for 0.3~0.7h to dewax it. The second step involves heating the sample to 1100±20℃ at a heating rate of 1~5℃ / min and holding it at that temperature for 0.5~1.5h, where ruthenium reacts with boron to form Ru7B3. The third step involves heating to 1200±20℃ at a heating rate of 10~20℃ / min and holding at that temperature for 0.5~1.5h, during which ruthenium reacts with boron to form Ru. 11 B8; The fourth step involves heating the sample to 1400±20℃ at a heating rate of 10~20℃ / min and holding it at that temperature for 0.5~1.5h, where ruthenium reacts with boron to form RuB. The fifth step involves heating the material to 1460±20℃ at a heating rate of 1~5℃ / min, and introducing argon gas until the ambient pressure reaches 3~6MPa. The material is then held at this temperature and pressure for 1~4 hours, allowing RuB to dissolve into the cobalt phase, thus strengthening the cobalt phase and completing the dewaxing and sintering process. Subsequently, the sintered billet was cooled in the furnace and removed, yielding a high-hardness, high-toughness, ultra-coarse-grained WC-Co cemented carbide strengthened by in-situ ruthenium boride. The carbide had an average grain size ≥8μm, metallographic characteristics of A02B00C00E00, a hardness ≥1100HV30, a bending strength ≥2100MPa, and a fracture toughness ≥22 MPa·m. 1 / 2 Thermal conductivity ≥140 W / m·K.

[0025] Example 1 In this embodiment, the RuB content in the cemented carbide is 0.5wt%, and the cobalt content is 6wt%.

[0026] Step 1: Prepare the ingredients.

[0027] Weigh out 4.517g of ruthenium powder with a purity of 99.99% and an FSSS of 1μm, 0.483g of boron powder with a purity of 99.99% and an FSSS of 1μm, 60g of cobalt powder with an FSSS of 1μm, and 935g of WC powder with an FSSS of 30μm, and set aside for later use.

[0028] Step 2: High-energy dry mixing.

[0029] The above raw materials are mixed, and the total carbon content of the mixture is adjusted to 6.14%. The mixture is then fed into a high-energy stirrer with inert gas protection. The ratio of powder volume to stirrer volume is 0.3, the high-energy stirring blade speed is 2000 rpm, and the stirring time is 6 hours to obtain a premix that has undergone the first activation.

[0030] Step 3: Flexible wet grinding.

[0031] The premixed material was added to a ball mill along with 30g of paraffin wax and 0.4L of hexane, and 1.2kg of Φ10.5×17mm grinding rods were added. The ratio of the total volume of the above materials to the volume of the wet grinding barrel of the ball mill was 0.5. The ball mill speed was 65rpm and the ball milling time was 8h to obtain a mixed slurry that had undergone a second activation.

[0032] Step 4: Drying and pressing.

[0033] The mixed slurry is dried under vacuum at 80°C, passed through a 60-mesh sieve, and held under pressure at 10 MPa for 8 seconds to obtain a pressed blank.

[0034] Step 5: Sintering.

[0035] The pressed blank is dewaxed and sintered according to the following process: Starting from room temperature, the temperature is increased to 400±10℃ at a rate of 5℃ / min and held for 0.5h. Then raise the temperature to 1100±10℃ at a rate of 5℃ / min and hold for 1 hour; Then raise the temperature to 1200±10℃ at a rate of 20℃ / min and hold for 1 hour; Then raise the temperature to 1400±10℃ at a rate of 20℃ / min and hold for 1 hour; Then, the temperature was increased to 1460±10℃ at a rate of 5℃ / min, and argon gas was introduced until the ambient pressure was 6MPa. The temperature and pressure were then maintained for 2 hours. After dewaxing and sintering, the blank is cooled in the furnace and removed to obtain an ultra-coarse-grained WC-6Co cemented carbide containing 0.5wt% ruthenium boride.

[0036] like Figure 2 The image shown is a metallographic diagram of this ultra-coarse-grained WC-6Co cemented carbide. Testing revealed that the metallographic characteristics of this ultra-coarse-grained WC-6Co cemented carbide are A02B00C00E00, with a grain size of 8.68 μm, a hardness of 1250 HV30, a bending strength of 2200 MPa, and a fracture toughness of 22.3 MPa·m. 1 / 2 Its thermal conductivity is 145 W / m·K.

[0037] Example 2 In this embodiment, the RuB content in the cemented carbide is 1.5wt%, and the cobalt content is 6wt%.

[0038] Step 1: Prepare the ingredients.

[0039] Weigh out 13.551g of ruthenium powder with a purity of 99.99% and an FSSS of 1μm, 1.449g of boron powder with a purity of 99.99% and an FSSS of 1μm, 60g of cobalt powder with an FSSS of 1μm, and 925g of WC powder with an FSSS of 30μm, and set aside for later use.

[0040] Step 2: High-energy dry mixing.

[0041] The above raw materials are mixed, and the total carbon content of the mixture is adjusted to 6.14%. The mixture is then fed into a high-energy stirrer with inert gas protection. The ratio of powder volume to stirrer volume is 0.3, the high-energy stirring blade speed is 2000 rpm, and the stirring time is 6 hours to obtain a premix that has undergone the first activation.

[0042] Step 3: Flexible wet grinding.

[0043] The premixed material was added together with 30g of paraffin wax and 0.4L of hexane into a ball mill, along with 1kg of Φ5.5×144.44mm grinding rods. The ratio of the total volume of the above materials to the volume of the wet grinding barrel of the ball mill was 0.5. The ball mill speed was 65rpm and the ball milling time was 6h to obtain a mixed slurry that had undergone a second activation.

[0044] Step 4: Drying and pressing.

[0045] The mixed slurry is dried under vacuum at 80°C, passed through a 60-mesh sieve, and held under pressure at 10 MPa for 8 seconds to obtain a pressed blank.

[0046] Step 5: Sintering.

[0047] The pressed blank is dewaxed and sintered according to the following process: Starting from room temperature, the temperature is increased to 400±10℃ at a rate of 5℃ / min and held for 0.5h. Then raise the temperature to 1100±10℃ at a rate of 5℃ / min and hold for 1 hour; Then raise the temperature to 1200±10℃ at a rate of 20℃ / min and hold for 1 hour; Then raise the temperature to 1400±10℃ at a rate of 20℃ / min and hold for 1 hour; Then, the temperature was increased to 1460±10℃ at a rate of 5℃ / min, and argon gas was introduced until the ambient pressure was 6MPa. The temperature and pressure were then maintained for 2 hours. After dewaxing and sintering, the blank is cooled in the furnace and removed to obtain an ultra-coarse-grained WC-6Co cemented carbide containing 1.5wt% ruthenium boride.

[0048] like Figure 3 The image shown is a metallographic diagram of this ultra-coarse-grained WC-6Co cemented carbide. Testing revealed that the metallographic characteristics of this ultra-coarse-grained WC-6Co cemented carbide are A02B00C00E00, with a grain size of 9.20 μm, a hardness of 1290 HV30, a bending strength of 2400 MPa, and a fracture toughness of 24.1 MPa·m. 1 / 2 Its thermal conductivity is 152 W / m·K.

[0049] Comparative Example 1 The difference between this comparative example and Example 1 is that the raw materials only include WC powder and Co powder, without the addition of ruthenium powder and boron powder.

[0050] Testing revealed that the WC-Co cemented carbide exhibits the following metallographic characteristics: A02B00C00E00; grain size: 8.50 μm; hardness: 850 HV30; bending strength: 1800 MPa; and fracture toughness: 18.0 MPa·m. 1 / 2 With a thermal conductivity of 145 W / m·K, the unstrengthened WC-Co cemented carbide has both low hardness and strength.

[0051] Comparative Example 2 The difference between this comparative example and Example 1 is that ruthenium powder and boron powder are replaced with Cr3C2, and the Cr3C2 content is 0.5wt%, that is, WC-6Co cemented carbide is prepared using conventional strengthening agents.

[0052] like Figure 4The image shown is a metallographic image of the WC-6Co cemented carbide containing 0.5 wt% Cr3C2 prepared in Comparative Example 2. Analysis revealed that the WC-6Co cemented carbide exhibits the following metallographic characteristics: A02B00C00E00; grain size: 6.50 μm; hardness: 1100 HV30; bending strength: 2200 MPa; and fracture toughness: 15.6 MPa·m. 1 / 2 The thermal conductivity is 125 W / m·K. Since Cr3C2 has the effect of inhibiting grain growth, while improving the strength of the alloy, it loses the toughness of the alloy. As a result, although the strength and hardness of the alloy are improved, the toughness is reduced, the grain size does not meet the requirements of ultra-coarse grains, and the thermal conductivity of the alloy is also reduced.

[0053] Comparative Example 3 The difference between this comparative example and Example 1 is that the second step of the high-energy stirring dry mixing process is omitted.

[0054] like Figure 5 The image shown is a metallographic image of the WC-Co cemented carbide prepared in Comparative Example 3 at low magnification without etching. The metallographic defects are severe, with numerous pores and cobalt pools. Because the metallographic structure of this WC-Co cemented carbide is unsatisfactory, no further characterization tests on its material properties will be conducted.

[0055] Test case Samples: Examples 1-2, Comparative Examples 1-3 The metallographic characteristics and material properties of the samples were tested, and the results are shown in Tables 1 and 2 below: Table 1. Results of metallographic characterization of different samples

[0056] Table 2. Material property test results of different samples

[0057] As can be seen from Tables 1 and 2 above, compared with Comparative Examples 1-3, Examples 1 and 2, using the alloy raw material formulation and preparation process proposed in this invention, produce WC-Co cemented carbides with an average grain size greater than 8 μm, meeting the requirements for ultra-coarse grains. The excessive fragmentation of WC particles and uneven distribution of the Co phase are significantly reduced, and the carbides exhibit significant advantages in overall material properties such as toughness, strength, and hardness. This demonstrates that the ultra-coarse grain WC-Co cemented carbides and their preparation method proposed in this invention can solve the problems of difficult control of grain size and morphology, low hardness, and poor toughness in existing ultra-coarse grain cemented carbides.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A ruthenium boride-strengthened ultra-coarse-grained WC-Co cemented carbide, characterized in that, By mass percentage, the raw materials include 0.5-5% ruthenium-boron mixed powder, 5-10% cobalt powder, and the balance being tungsten carbide particles; The ruthenium-boron mixed powder has an atomic ratio of 1:0.5-1.5, and the total mass of tungsten and carbon in the tungsten carbide particles ranges from 6.08 to 6.20 wt%.

2. The ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 1, characterized in that, The FSSS of tungsten carbide particles is 25~30μm.

3. A method for preparing the ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide as described in claim 1 or 2, characterized in that, Includes the following steps: S1 Take the raw materials according to the specified amount, place them in a mixer, and stir at a speed of 1000~5000 rpm to carry out the first activation treatment and obtain the premix; S2 The premixed material, molding agent, wet grinding media, and grinding media are placed in a ball mill and wet-milled to undergo a second activation treatment to obtain a mixed slurry; the mixed slurry is dried, sieved, and pressed to obtain a pressed compact; S3 The compact is placed in a sintering furnace, subjected to gradient heating, dewaxing and sintering, then cooled with the furnace and removed to obtain the ultra-coarse-grained WC-Co cemented carbide.

4. The method for preparing ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 3, characterized in that, In step S1, the ratio of the total volume of raw materials to the volume of the agitator is 0.2 to 0.

3.

5. The method for preparing ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 3, characterized in that, In step S1, the stirring time is 4~12 hours.

6. The method for preparing ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 3, characterized in that, In step S2, the volume ratio of the mixed slurry to the ball mill capacity is 0.4 to 0.

5.

7. The method for preparing ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 3, characterized in that, In step S2, during wet grinding, the grinding speed is 60~80 rpm, the ball-to-material ratio is 0.5~1.2:1, and the wet grinding time is 4~10h.

8. The method for preparing ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 3, characterized in that, In step S2, the grinding media are coarse rods with a diameter of 10.5*17mm and / or fine rods with a diameter of 5.5*14.4mm.

9. The method for preparing ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 3, characterized in that, In step S2, the pressing pressure is 10~12MPa and the holding time is 5~10s.

10. The method for preparing the ruthenium boride-reinforced ultra-coarse-grained WC-Co cemented carbide according to claim 3, characterized in that, In step S3, during the gradient heating, the temperature is controlled as follows: The first step is to start from room temperature, heat to 400±20℃ at a heating rate of 1~5℃ / min, and hold at that temperature for 0.3~0.7h to dewax. The second step is to heat the sample to 1100±20℃ at a heating rate of 1~5℃ / min and hold it at that temperature for 0.5~1.5h. The third step is to heat the sample to 1200±20℃ at a heating rate of 10~20℃ / min and hold it at that temperature for 0.5~1.5h. The fourth step is to heat the sample to 1400±20℃ at a heating rate of 10~20℃ / min and hold it at that temperature for 0.5~1.5h. The fifth step involves heating the material to 1460±20℃ at a heating rate of 1~5℃ / min, and introducing argon gas until the ambient pressure reaches 3~6MPa. The material is then held under these conditions for 1~4 hours to complete the dewaxing and sintering process.

Images